Drilling motors are used as part of a drill string, near the drill head, to drive the drill head rotationally relative to the upwardly continuing drill string. The drilling fluid flow is usually used to power the motor. Drilling motors are often used on coiled tubing which cannot be rotated. In some cases the motor is used to rotationally attach the drill string to hardware down hole that is to be recovered by tension forces. Jars are sometimes used to deliver shock to the hardware. Motors that are designed for drilling are sometimes not designed to accept axial shock forces.
Axial shock loads imposed upon motors can separate their Output drive shafts. The usual structure of motors includes capture rings that will usually extract all of the output shaft when the damaged motor is removed from the well. The part of the output shaft that extends outside the motor body is about the size of the body. The shaft diameter decreases before the capture contrivance can engage the shaft. If the shaft breaks below the capture device, debris is left in the well.
The U.S. Pat. No. 7,445,061 issued Nov. 4, 2008 provided a sleeve that engaged the largest part of the output shaft and extended upward to engage at least some of the thrust bearings. That enabled the recovery of all motor parts and the bit even if the shaft broke below the capture device.
During the use of drilling motors, the motors may be miles below the surface and the evidence of failing bearings may not be realized until the bearings are destroyed and the supported shaft drops out of the motor. The cited patent depends upon bearings to support the output shaft and these bearings too can fail totally. The present improvement can function independently of any bearings. Further, the friction of the preferred configuration makes the motor have to produce more torque, or stall, when the bearings have failed. This additional torque can be detected in the form of a mud pressure jump at the stand pipe. The machine can be stopped before the capture device is destroyed.